This invention relates to an electronic musical instrument such as a music synthesizer with a bender.
Music synthesizers are usually constructed such that several pitch variations are given to the generated tone by operating a pitch bend wheel. However, slight variations of the pitch of the output tone are liable to result even when the music synthesizer is played without operating the pitch bend wheel. This is caused by output characteristics of an analog-to-digital (A/D) converter which is used to convert the analog output signal from the pitch bend into a digital signal. For example, in the case of a successive approximate type A/D converter, the least significant bit (LSB) of the digital output of the A/D converter is influenced by errors of resistor elements used in the A/D converter so that it randomly takes value "1" or "0".
Meanwhile, in the A/D converter, the pitch bend output is sampled and digitally converted in a constant cycle, e.g., 8 milliseconds. Therefore, when the pitch bend wheel is quickly operated in the sampling cycle period of 8 milliseconds, the A/D converter output cannot correctly follow the pitch bend effect. To cope with this deficiency, the sampling cycle may be reduced. In this case, the time exclusively used for the pitch bend processing among the operation time of a CPU which controls the operation of the music synthesizer is increased, which is liable to have an adverse effect on the control of operation of the entire music synthesizer.